The present invention relates to the dewatering to a desired concentration of fiber-containing material in suspension, especially cellulose pulp, obtained through delignification of wood or other fiber containing material.
Prior art dewatering apparatus has usually fallen into one of the following classes: one or more perforated rotating drums in a trough; presses with two or more perforated or non-perforated rolls; screw presses; and centrifugal devices. The device according to the present invention combines the rotating drums in a trough and roll press concepts into an improved device. Prior art dewatering devices are usually of an open design, whereby air may contact the pulp suspension, while according to the apparatus of the present invention dewatering takes place in a closed space so that the chances of air contacting the suspension are greatly diminished.
According to the method of the present invention, a pulp suspension is dewatered to a solids concentration that is higher than the desired concentration, and thereafter a quantity of liquid is added thereto to obtain the desired solids concentration of the pulp. The added liquid passes through perforations in the drums according to the present invention, resulting in cleaning thereof.
It is the primary object of the present invention to provide improved pulp dewatering apparatus, and an improved method for pulp dewatering. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.